Sexual Maturity in Girls Influenced by 'Imprinted' Genes from Different Parents

How long does it take a girl to reach maturity? It depends a lot on their genes. It turns outs that the age at which girls reach sexual maturity is influenced by "imprinted genes," which are a small sub-set of genes whose activity differs depending on which parent passes on that gene.

"Normally, our inherited physical characteristics reflect a roughly average combination of our parents' genomes, but imprinted genes place unequal weight on the influence of either the mother's or the father's genes," said John Perry, one of the researchers, in a news release. "Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent."

In order to better understand puberty in women, the researchers examined more than 180,000 women. More specifically, they identified 123 genetic variations that were associated with the timing of when girls experienced their first menstrual cycle by analyzing the DNA of 182,416 women of European descent.

The activity of imprinted genes differs depending on which parent the gene is inherited from. For example, some genes are only active when inherited from the mother, while others are only active when inherited from the father. Both types of these imprinted genes were identified as determining puberty timing in girls. This suggests a possible biological conflict between the parents of their child's rate of development.

"We knew that some imprinted genes control antenatal growth and development-but there is increasing interest in the possibility that imprinted genes may also control childhood maturation and later life outcomes, including disease risks," said Perry.

The findings reveal that while lifestyle factors do play a role in puberty, there's also a wide and complex network of genetic factors. The research could help scientists find out why early puberty in girls is linked to higher risks of developing diabetes, heart disease and breast cancer later in life.

The findings are published in the journal Nature.